[Choosing wisely recommendations in hematology and oncology]. / Klug-entscheiden-Empfehlungen in der Hämatologie und Onkologie.

Many new diagnostic and therapeutic options have been introduced in the field of hematology and medical oncology during recent years. Rational treatment recommendations are thus of even greater importance. Five presumably underused measures are recommended (positive recommendations), primarily pertaining to supportive therapy, but also concerning the selective use of molecular diagnostics. Recommendations to avoid unnecessary procedures (negative recommendations) involve a possible excessive use of anticancer therapy and imaging, and insufficiently selective use of growth factors, antiemetics, and targeted therapies.

Immature platelets do not reliably predict platelet recovery in patients with intensive chemotherapy or stem cell transplantation.

BACKGROUND AND OBJECTIVES: It has been reported that immature platelets may indicate imminent platelet (PLT) recovery following intensive chemotherapy and/or haematopoietic stem cell transplantation with the perspective to withhold unnecessary transfusions. The objective of our prospective study was to test immature PLTs as measured by two haematology analysers to predict PLT recovery. MATERIAL AND METHODS: This study monitored 51 courses of severe thrombocytopenia after chemotherapy in 35 adult haematology/oncology patients starting at a PLT count <70 × 109 /l until PLT recovery (>20 × 109 /l) or discharge from hospital. Immature platelets as measured by immature platelet fraction (IPF) (Sysmex XE-5000) and retPLT (Abbott CD-Sapphire) as well as reticulocyte and leucocyte count were evaluated regarding their usefulness to predict PLT recovery. Furthermore, the influence of platelet concentrate (PC) transfusions upon IPF and retPLT was assessed. RESULTS: With beginning of thrombocytopenia, most patients demonstrated elevated IPF% (median 8·6%) and retPLT% (median 6·8%). These elevated values significantly dropped after transfusions of PCs. IPF and retPLT values during nadir and at imminent PLT recovery were largely overlapping and receiver operating characteristics analysis demonstrated poor separation between both clinical situations. A reasonable cut-off could not be established to prospectively predict imminent PLT recovery for either of the parameters investigated. CONCLUSION: Measurements of IPF and retPLT lack predictive power regarding imminent PLT recovery in patients with severe thrombocytopenia following intensive chemotherapy. Decisions regarding prophylactic PC transfusions should not be based on these parameters.

High-dose methotrexate-based immuno-chemotherapy for elderly primary CNS lymphoma patients (PRIMAIN study).

To investigate immuno-chemotherapy for elderly immuno-competent patients (⩾65 years) with newly diagnosed primary central nervous system lymphoma, we conducted a multicentre single-arm trial. One cycle consisted of rituximab (375 mg/m2, days 1, 15, 29), high-dose methotrexate (3 g/m2 days 2, 16, 30), procarbazine (60 mg/m2 days 2-11) and lomustine (110 mg/m2, day 2)-R-MPL protocol. Owing to infectious complications, we omitted lomustine during the study and consecutive patients were treated with the R-MP protocol. Three cycles were scheduled and repeated on day 43. Subsequently, patients commenced 4 weekly maintenance treatment with procarbazine (100 mg for 5 days). Primary end point was complete remission (CR) after 3 cycles. We included 107 patients (69 treated with R-MPL and 38 with R-MP). In all, 38/107 patients achieved CR (35.5%) and 15 (14.0%) achieved partial remission. R-MP was associated with a lower CR rate (31.6%) compared with R-MPL (37.7%), but respective 2-year progression-free survival (All 37.3%; R-MP 34.9%; R-MPL 38.8%) and overall survival (All 47.0%; R-MP 47.7%; R-MPL 46.0%) rates were similar. R-MP was associated with less ⩾grade 3 toxicities compared with R-MPL (71.1% vs 87.0%). R-MP is more feasible while still associated with similar efficacy compared with R-MPL and warrants further improvement in future studies.

Diagnosis of invasive fungal infections in haematological patients by combined use of galactomannan, 1,3-ß-D-glucan, Aspergillus PCR, multifungal DNA-microarray, and Aspergillus azole resistance PCRs in blood and bronchoalveolar lavage samples: results of a prospective multicentre study.

High mortality rates of invasive fungal disease (IFD), especially invasive aspergillosis (IA), in immunocompromised haematological patients and current diagnostic limitations require improvement of detection of fungal pathogens by defining the optimal use of biomarkers and clinical samples. Concurrent bronchoalveolar lavage (BAL) and peripheral blood samples of 99 haematological patients with suspected IFD were investigated within a multicentre prospective study. Diagnostic performance of a galactomannan (GM) enzyme immune assay (EIA), a 1,3-ß-D-glucan assay (BDG), an Aspergillus PCR, and a multifungal DNA-microarray (Chip) alone or in combination were calculated. IFD were classified as proven (n=3), probable (n=34), possible (n=33), and no IFD (n=29) according to EORTC/MSG criteria. GM, PCR, and Chip showed superior diagnostic performance in BAL than in blood, whereas specificity of BDG in BAL was poor (48% (14/29)). The combination of GM (BAL) with BDG (blood) showed sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and DOR (diagnostic odds ratio) of 92% (34/37), 93% (27/29), 94%, 90%, and 153.0, respectively. Combining GM (BAL) with PCR (BAL) showed convincing diagnostic potential for diagnosing IA with sensitivity, specificity, PPV, NPV, and DOR of 85% (17/20), 97% (28/29), 94%, 90%, and 158.7. Addition of the DNA-microarray resulted in further detection of two mucormycetes infections. In 1 out of 15 Aspergillus DNA-positive samples a triazole resistance-mediating Cyp51A mutation was found. Combination of biomarkers is superior to their sole use in diagnosing IFD, particularly IA. Integrating blood and BAL samples into a diagnostic algorithm is an advantageous approach.

Secondary malignancies in chronic myeloid leukemia patients after imatinib-based treatment: long-term observation in CML Study IV.

Treatment of chronic myeloid leukemia (CML) has been profoundly improved by the introduction of tyrosine kinase inhibitors (TKIs). Long-term survival with imatinib is excellent with a 8-year survival rate of ∼88%. Long-term toxicity of TKI treatment, especially carcinogenicity, has become a concern. We analyzed data of the CML study IV for the development of secondary malignancies. In total, 67 secondary malignancies were found in 64 of 1525 CML patients in chronic phase treated with TKI (n=61) and interferon-α only (n=3). The most common malignancies (n⩾4) were prostate, colorectal and lung cancer, non-Hodgkin's lymphoma (NHL), malignant melanoma, non-melanoma skin tumors and breast cancer. The standardized incidence ratio (SIR) for all malignancies excluding non-melanoma skin tumors was 0.88 (95% confidence interval (0.63-1.20)) for men and 1.06 (95% CI 0.69-1.55) for women. SIRs were between 0.49 (95% CI 0.13-1.34) for colorectal cancer in men and 4.29 (95% CI 1.09-11.66) for NHL in women. The SIR for NHL was significantly increased for men and women. An increase in the incidence of secondary malignancies could not be ascertained. The increased SIR for NHL has to be considered and long-term follow-up of CML patients is warranted, as the rate of secondary malignancies may increase over time.

Karyotype complexity and prognosis in acute myeloid leukemia.

A complex aberrant karyotype consisting of multiple unrelated cytogenetic abnormalities is associated with poor prognosis in patients with acute myeloid leukemia (AML). The European Leukemia Net classification and the UK Medical Research Council recommendation provide prognostic categories that differ in the definition of unbalanced aberrations as well as the number of single aberrations. The aim of this study on 3526 AML patients was to redefine and validate a cutoff for karyotype complexity in AML with regard to adverse prognosis. Our study demonstrated that (1) patients with a pure hyperdiploid karyotype have an adverse risk irrespective of the number of chromosomal gains, (2) patients with translocation t(9;11)(p21∼22;q23) have an intermediate risk independent of the number of additional aberrations, (3) patients with ⩾4 abnormalities have an adverse risk per se and (4) patients with three aberrations in the absence of abnormalities of strong influence (hyperdiploid karyotype, t(9;11)(p21∼22;q23), CBF-AML, unique adverse-risk aberrations) have borderline intermediate/adverse risk with a reduced overall survival compared with patients with a normal karyotype.

Azacitidine in combination with intensive induction chemotherapy in older patients with acute myeloid leukemia: The AML-AZA trial of the Study Alliance Leukemia.

DNA methylation changes are a constant feature of acute myeloid leukemia. Hypomethylating drugs such as azacitidine are active in acute myeloid leukemia (AML) as monotherapy. Azacitidine monotherapy is not curative. The AML-AZA trial tested the hypothesis that DNA methyltransferase inhibitors such as azacitidine can improve chemotherapy outcome in AML. This randomized, controlled trial compared the efficacy of azacitidine applied before each cycle of intensive chemotherapy with chemotherapy alone in older patients with untreated AML. Event-free survival (EFS) was the primary end point. In total, 214 patients with a median age of 70 years were randomized to azacitidine/chemotherapy (arm-A) or chemotherapy (arm-B). More arm-A patients (39/105; 37%) than arm-B (25/109; 23%) showed adverse cytogenetics (P=0.057). Adverse events were more frequent in arm-A (15.44) versus 13.52 in arm-B, (P=0.26), but early death rates did not differ significantly (30-day mortality: 6% versus 5%, P=0.76). Median EFS was 6 months in both arms (P=0.96). Median overall survival was 15 months for patients in arm-A compared with 21 months in arm-B (P=0.35). Azacitidine added to standard chemotherapy increases toxicity in older patients with AML, but provides no additional benefit for unselected patients.

Safety and efficacy of imatinib in CML over a period of 10 years: data from the randomized CML-study IV.

Tyrosine kinase inhibitors (TKI) have changed the natural course of chronic myeloid leukemia (CML). With the advent of second-generation TKI safety and efficacy issues have gained interest. The randomized CML - Study IV was used for a long-term evaluation of imatinib (IM). 1503 patients have received IM, 1379 IM monotherapy. After a median observation of 7.1 years, 965 patients (64%) still received IM. At 10 years, progression-free survival was 82%, overall survival 84%, 59% achieved MR(5), 72% MR(4.5), 81% MR(4), 89% major molecular remission and 92% MR(2) (molecular equivalent to complete cytogenetic remission). All response levels were reached faster with IM800 mg except MR(5). Eight-year probabilities of adverse drug reactions (ADR) were 76%, of grades 3-4 22%, of non-hematologic 73%, and of hematologic 28%. More ADR were observed with IM800 mg and IM400 mg plus interferon α (IFN). Most patients had their first ADR early with decreasing frequency later on. No new late toxicity was observed. ADR to IM are frequent, but mostly mild and manageable, also with IM 800 mg and IM 400 mg+IFN. The deep molecular response rates indicate that most patients are candidates for IM discontinuation. After 10 years, IM continues to be an excellent initial choice for most patients with CML.

Velocity of early BCR-ABL transcript elimination as an optimized predictor of outcome in chronic myeloid leukemia (CML) patients in chronic phase on treatment with imatinib.

UNLABELLED: Early assessment of response at 3 months of tyrosine kinase inhibitor treatment has become an important tool to predict favorable outcome. We sought to investigate the impact of relative changes of BCR-ABL transcript levels within the initial 3 months of therapy. In order to achieve accurate data for high BCR-ABL levels at diagnosis, beta glucuronidase (GUS) was used as a reference gene. Within the German CML-Study IV, samples of 408 imatinib-treated patients were available in a single laboratory for both times, diagnosis and 3 months on treatment. In total, 301 of these were treatment-naïve at sample collection. RESULTS: (i) with regard to absolute transcript levels at diagnosis, no predictive cutoff could be identified; (ii) at 3 months, an individual reduction of BCR-ABL transcripts to the 0.35-fold of baseline level (0.46-log reduction, that is, roughly half-log) separated best (high risk: 16% of patients, 5-year overall survival (OS) 83% vs 98%, hazard ratio (HR) 6.3, P=0.001); (iii) at 3 months, a 6% BCR-ABL(IS) cutoff derived from BCR-ABL/GUS yielded a good and sensitive discrimination (high risk: 22% of patients, 5-year OS 85% vs 98%, HR 6.1, P=0.002). Patients at risk of disease progression can be identified precisely by the lack of a half-log reduction of BCR-ABL transcripts at 3 months.

Isolated late metastasis from testicular seminoma presenting as a parotid gland mass: case report and review of the literature.

Parotid metastases from non-head-and-neck cancers are rare and may represent a diagnostic and therapeutic challenge. A late metastasis to the parotid gland from a seminoma is an unusual manifestation of disease. A 45-year-old man with a history of testicular seminoma 5 years earlier presented with a rapidly progressing parotid mass. Ultrasonography and computed tomography showed a space-occupying lesion at the angle of the right jaw. The mass was infiltrating into the parotid gland and into the parapharyngeal space. A primary parotid neoplasm was suspected, and panendoscopy combined with open biopsy was performed. Histology examination confirmed a seminoma metastatic to the parotid gland, and comparison with the primary tumour showed identical histology. The patient received chemotherapy for recurrent seminoma in accordance with the pei (cisplatin, etoposide, ifosfamide) protocol. After 4 courses of chemotherapy, salvage radical parotidectomy with removal of all suspicious residual tumour tissue was performed. This case illustrates the difficulties that may be encountered in the differential diagnosis of parotid gland masses and underlines the necessity for a detailed clinical history and for strong interdisciplinary collaboration between oncologists and pathologists to correctly diagnose cases with such unusual presentations.

Primary prophylaxis of bacterial infections and Pneumocystis jirovecii pneumonia in patients with hematological malignancies and solid tumors : guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Oncology (DGHO).

Bacterial infections are the most common cause for treatment-related mortality in patients with neutropenia after chemotherapy. Here, we discuss the use of antibacterial prophylaxis against bacteria and Pneumocystis pneumonia (PCP) in neutropenic cancer patients and offer guidance towards the choice of drug. A literature search was performed to screen all articles published between September 2000 and January 2012 on antibiotic prophylaxis in neutropenic cancer patients. The authors assembled original reports and meta-analysis from the literature and drew conclusions, which were discussed and approved in a consensus conference of the Infectious Disease Working Party of the German Society of Hematology and Oncology (AGIHO). Antibacterial prophylaxis has led to a reduction of febrile events and infections. A significant reduction of overall mortality could only be shown in a meta-analysis. Fluoroquinolones are preferred for antibacterial and trimethoprim-sulfamethoxazole for PCP prophylaxis. Due to serious concerns about an increase of resistant pathogens, only patients at high risk of severe infections should be considered for antibiotic prophylaxis. Risk factors of individual patients and local resistance patterns must be taken into account. Risk factors, choice of drug for antibacterial and PCP prophylaxis and concerns regarding the use of prophylactic antibiotics are discussed in the review.

T lymphocytes can be effectively recruited for ex vivo and in vivo lysis of AML blasts by a novel CD33/CD3-bispecific BiTE antibody construct.

Patients with acute myelogenous leukemia (AML) are in high need of novel targeted therapies. Here we explored the ex vivo activity of AMG330, a novel T-cell-engaging BiTE (bi-specific T-cell engagers) antibody (Ab) construct, that is bispecific for the myeloid differentiation antigen, CD33 and CD3, in primary samples from AML patients (N=23) and AML cell lines. KG-1 and U937 cells were lysed in co-culture with healthy donor T-cells at AMG330 concentrations as low as 0.1 ng/ml (1.8 pM). T-cells derived from AML patient samples were found to be as active in redirected lysis by AMG330 as T-cells from healthy donors. In an autologous setting, AMG330 could activate and expand T-cells in primary AML patient samples, and effectively mediated the redirected lysis of AML blasts and normal myeloid cells. A deficiency in target-cell lysis was only observed in samples with very low initial effector-to-target (E:T) ratio. However, this could be overcome if previously stimulated autologous T-cells were tested in patient samples at a higher E:T ratio. In vivo experiments in immunodeficient mice demonstrated significant inhibition of tumor growth by AMG330 and an inducible infiltration of human T-cells into subcutaneous HL60 tumors. The activities of the CD33/CD3-bispecific BiTE Ab construct AMG330 warrant further development for the treatment of AML.

Early molecular and cytogenetic response is predictive for long-term progression-free and overall survival in chronic myeloid leukemia (CML).

In the face of competing first-line treatment options for CML, early prediction of prognosis on imatinib is desirable to assure favorable survival or otherwise consider the use of a second-generation tyrosine kinase inhibitor (TKI). A total of 1303 newly diagnosed imatinib-treated patients (pts) were investigated to correlate molecular and cytogenetic response at 3 and 6 months with progression-free and overall survival (PFS, OS). The persistence of BCR-ABL transcript levels >10% according to the international scale (BCR-ABL(IS)) at 3 months separated a high-risk group (28% of pts; 5-year OS: 87%) from a group with >1-10% BCR-ABL(IS) (41% of pts; 5-year OS: 94%; P=0.012) and from a group with ≤1% BCR-ABL(IS) (31% of pts; 5-year OS: 97%; P=0.004). Cytogenetics identified high-risk pts by >35% Philadelphia chromosome-positive metaphases (Ph+, 27% of pts; 5-year OS: 87%) compared with ≤35% Ph+ (73% of pts; 5-year OS: 95%; P=0.036). At 6 months, >1% BCR-ABL(IS) (37% of pts; 5-year OS: 89%) was associated with inferior survival compared with ≤1% (63% of pts; 5-year OS: 97%; P<0.001) and correspondingly >0% Ph+ (34% of pts; 5-year OS: 91%) compared with 0% Ph+ (66% of pts; 5-year OS: 97%; P=0.015). Treatment optimization is recommended for pts missing these landmarks.

[Hemolytic anemias in adults]. / Hämolytische Anämien beim Erwachsenen.

The erythrocyte lifespan in haemolytic anemia is shortened while erythropoesis is increased. Important labaratory findings are increased reticulocytes, LDH, indirect bilirubin and a decreased haptoglobin level. The most important diagnostic tool for further work up of hemolytic anemia is the direct antiglobulin test (DAT, Coombs test) to differentiate autoimmune hemolytic anemia (AIHA) from other causes. Another important group are fragmentation syndroms (hemolytic uremic syndrome and thrombotic thrombocytopenic purpura). In these forms of haemolytic anemia fragmented red blood cells can be found in the blood smear together with thrombocytopenia. A severe problem in paroxysmal nocturnal hematuria is the incidence of thrombosis. The following review describes the most important forms of hemolytic anemia in the adult and the diagnostic and therapeutic strategies.

[Chronic myeloproliferative diseases. Current therapeutic standards and new developments]. / Chronische myeloproliferative Erkrankungen. Aktuelle Therapiestandards und neue Entwicklungen.

Chronic myeloproliferative diseases (CMPD) are haematopoetic neoplasias with indolent course and preserved cellular function of the maturing malignant cells. In Philadelphia-positive chronic myeloid leukaemia the discovery of molecular disease mechanisms led to the successful introduction of targeted therapy with imatinib. Ph-negative CMPD are conventionally treated by cytoreduction and low dose ASS in order to minimise the risk of vascular complications. For all CMPD, lifelong surveillance and therapy are necessary.

Dynamics of BCR-ABL mRNA expression in first-line therapy of chronic myelogenous leukemia patients with imatinib or interferon alpha/ara-C.

We sought to determine dynamics of BCR-ABL mRNA expression levels in 139 patients with chronic myelogenous leukemia (CML) in early chronic phase, randomized to receive imatinib (n=69) or interferon (IFN)/Ara-C (n=70). The response was sequentially monitored by cytogenetics from bone marrow metaphases (n=803) and qualitative and quantitative RT-PCR from peripheral blood samples (n=1117). Complete cytogenetic response (CCR) was achieved in 60 (imatinib, 87%) vs 10 patients (IFN/Ara-C, 14%) after a median observation time of 24 months. Within the first year after CCR, best median ratio BCR-ABL/ABL was 0.087%, (imatinib, n=48) vs 0.27% (IFN/Ara-C, n=9, P=0.025). BCR-ABL was undetectable in 25 cases by real-time PCR, but in only four patients by nested PCR. Median best response in patients with relapse after CCR was 0.24% (n=3) as compared to 0.029% in patients with continuous remission (n=52, P=0.029). We conclude that (i) treatment with imatinib in newly diagnosed CML patients is associated with a rapid decrease of BCR-ABL transcript levels; (ii) nested PCR may reveal residual BCR-ABL transcripts in samples that are negative by real-time PCR; (iii) BCR-ABL transcript levels parallel cytogenetic response, and (iv) imatinib is superior to IFN/Ara-C in terms of the speed and degree of molecular responses, but residual disease is rarely eliminated.

Blood leukocyte subsets and cytokine profile after autologous peripheral blood stem cell transplantation.

High-dose chemotherapy with autologous peripheral blood stem cell transplantation (PBSCT) includes the risk of infectious complications due to neutropenia and therapy-induced immune deviation. In order to understand early immune recovery in this situation, we analyzed the distribution of cell subsets by flow cytometry and we measured cytokine production in a whole blood assay stimulated with lipopolysaccharide (LPS) in order to induce monocyte (MO) activation in 43 patients with solid tumors or lymphoma treated with two cycles of high-dose chemotherapy and PBSCT. Blood was collected at the following time points: before start of mobilization chemotherapy, before and after high-dose chemotherapy, and 10 and 30 days after PBSCT. In the lymphocyte compartment, we found a depletion of B cells and naive T cells and a transitory reduction of natural killer (NK) cells, whereas MO and neutrophils recovered rapidly. However, during early recovery, HLA-DR expression on MO and the percentage of CD16(+) MO was considerably reduced. Production of proinflammatory cytokines interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-alpha upon LPS stimulation was severely impaired directly after chemotherapy and unexpectedly remained low during early recovery of myeloid cells, whereas production of IL-1RA was enhanced, indicating a shift of immune competent cells to an anti-inflammatory or anergic state early after PBSCT.

[The "classical" macrophage marker CD68 is strongly expressed in primary human fibroblasts]. / Der "klassische" Makrophagenmarker CD68 ist in primären humanen Fibroblasten stark exprimiert.

AIM: Monoclonal antibodies against the human homologue of mouse macrosialin, CD68, are generally commercialized as markers for human monocytes and macrophages. Indeed, CD68 is considered as a selective marker for human myeloid cells, although several previous immunohistochemical studies indicate that some antibody clones also react with other hematopoietic and non-hematopoietic cell types. The aim of our study was to verify these observations and to evaluate the reliability of CD68 as a macrophage marker. METHODS: We investigated protein and RNA expression of CD68 in various fibroblast types and carcinoma cell lines as compared to monocytes and macrophages using immunohistochemistry, flow cytometry, and specific RT-PCR. Different monoclonal antibody clones against CD68 were applied including KP-1 and EBM11. RESULTS: As expected, the intensity of immunohistochemical and flow cytometric CD68 staining was dependent on both the antibody clone and the fixation procedure. However, fibroblasts isolated from normal skin, normal breast, breast tumor tissue, and osteoarthritis synovia clearly expressed CD68 protein at levels comparable to macrophages. The specificity of CD68 expression in fibroblasts was verified by RT-PCR which also showed some tumor cell types to express CD68 mRNA. CONCLUSION: Our findings clearly demonstrate that the expression of CD68 is not restricted to the macrophage lineage. This is highly relevant for experimental and diagnostic purposes, since anti CD68 antibodies cannot be accepted without reservations for the discrimination of myeloid cells and fibroblasts even in paraffin sections after formalin fixation.

Activation of lymphocytes inhibits human monocyte to macrophage differentiation.

Tissue macrophages (MAC) differentiate from circulating blood monocytes (MO) during a maturation step that is of crucial importance for their functional competence. In vitro a similar process of maturation can be observed, if MO are cultured in the presence of serum. In the work presented here, we show that activated lymphocytes can interfere with MAC differentiation. Resting lymphocytes have only marginal influence upon MO to MAC transition in vitro. However, if cells are activated by the lectins PWM or ConA or by double-stranded RNA (polyinosinic-polycytidylic acid, pI:C), normal MAC maturation is suppressed: MO stay small and do not acquire MAC maturation-associated surface molecules like carboxypeptidase M (CPM, determined by antibody MAX.1) or CD84 (determined by antibody MAX.3). This phenomenon can be induced by small numbers of lymphocytes and can be transmitted by soluble factors in cultures stimulated with ConA or PWM. IFN-gamma is present in these conditioned media and partially suppresses MAC maturation but cannot fully substitute for the conditioned media. On the contrary, in pI:C stimulated cultures, suppression of MAC differentiation is dependent on cell-cell contact. In conclusion, activated lymphocytes are able to suppress the terminal differentiation of MAC by several pathways depending on the mode of lymphocyte stimulation.

Decreased T cell stimulatory capacity of monocyte-derived human macrophages following herpes simplex virus type 1 infection.

Macrophages play a central role in establishing a specific immune response by acting as professional antigen presenting cells (APC) for T cells leading to a vigorous immune response. In order to analyze if Herpes simplex Virus (HSV) type 1 infection might affect the macrophage APC-function, monocyte-derived human macrophages were infected with HSV-1 strain F in vitro. Cocultures with allogeneic T cells revealed a strongly impaired stimulatory capacity of HSV-infected macrophages compared to uninfected controls which was not owing to a productive viral infection in macrophages. An increased expression of Fas ligand (FasL/CD95L) was detected in HSV-infected macrophages by FACS analysis. Although the majority of the macrophages expressed high levels of Fas (CD95/Apo-1), the HSV-induced upregulation of FasL did not result in an increased autocrine apoptosis of macrophages which might be related to endogenous expression of the apoptosis inhibitor FLICE inhibitory protein (FLIP). However, substantial apoptosis occurred in peripheral T cells as well as Fas-sensitive Jurkat T cells when cocultured with HSV-infected macrophages. These findings suggest that the paracrine killing of activated T cells by FasL expressing APC might be a novel strategy of immune evasion by HSV.